Above-bandgap optical anisotropies in cubic semiconductors: A visible-near ultraviolet probe of surfaces
Above-bandgap optical anisotropies in cubic semiconductors: A visible-near ultraviolet probe of surfaces
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立方半导体中的带隙以上光学各向异性：表面可见光-近紫外探针
DOI：
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发表时间：
1985
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影响因子：
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通讯作者：
D. Aspnes
中科院分区：
文献类型：
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作者：
D. Aspnes
本文描述了首次系统研究立方半导体带隙以上光学各向异性的一些结果。各向异性很大，约为沿各向异性相介质张量正交主轴偏振光的相对反射率差的1%。确定了由各向异性表面膜、物理吸附分子和化学吸附引起的衬底原子最外层电子极化率变化引起的外在贡献。这些反射率-差（RD）光谱的线形为描述这些材料光学各向异性的内在贡献的模型提供了第一个关键测试。主要的本征贡献显示为表面（界面）多体效应，由于体晶格的终止导致表面原子的屏蔽减少。空间色散对带间能隙影响的二次本征贡献。
I describe some results of the first systematic study of above‐bandgap optical anisotropies in cubic semiconductors. The anisotropies are large, of the order of 1% of the relative reflectance differences for light polarized along orthogonal principal axes of the dielectric tensor of the anisotropic phase. Extrinsic contributions arising from anisotropic surface films, physisorbed molecules, and chemisorption‐induced changes in the electronic polarizability of the outermost plane of substrate atoms are identified. The line shapes of these reflectance‐difference (RD) spectra provide the first critical test of models proposed to describe intrinsic contributions to the optical anisotropies of these materials. The dominant intrinsic contribution is shown to be a surface (interface) many‐body effect due to the reduced screening of the surface atoms as a result of the termination of the bulk lattice. A secondary intrinsic contribution from the influence of spatial dispersion on interband energy gaps in the one‐e...